NatGeo-PhotoContest-Downloader.ps1

#-------------------------------------------------------------------------------
# Downloads photos from National Geographic's Photo Contest
#-------------------------------------------------------------------------------
param($res = '1280', $year = '2008')

$client = New-Object System.Net.WebClient
$client.Headers.Add('User-agent', 'Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; .NET CLR 1.0.3705;)')

$prefixes = @{
    '2008' = @('1107', '1103', '1027', '1020', '1014', '1006', '0929', '0922', 
               '0915', '0908', '0901', '0825', '0818', '0811');
    '2009' = @('1109', '1102', '1026', '1019', '1013', '1005', '0928', '0921',
               '0914', '0907', '0831', '0824', '0817')
}

function Get-ImageFromNatGeo($name) {

    if ($year -eq '2009') {
        $uri = New-Object Uri("http://ngm.nationalgeographic.com/photo-contest/2009/img/wallpaper/$name")
    } else {
        $uri = New-Object Uri("http://ngm.nationalgeographic.com/photo-contest/img/wallpaper/$name")
    }
    
    "Downloading $uri to $name..."

    $client.DownloadFile($uri, $name)
}

foreach ($i in 1..26) {
    foreach ($prefix in $prefixes[$year]) {
        $name = '{0}wallpaper-{1}_{2}.jpg' -f $prefix, $i, $res
        Get-ImageFromNatGeo $name
    }
}